1. Field of the Invention
The present invention relates to a method for bonding a semiconductor chip, and in particular to a method for bonding a semiconductor chip wherein a separate flipping process is not required by mounting a wafer in a manner the a front surface of the wafer is faces downward and then pushed a die downward to a tray therebelow.
2. Description of the Related Art
A plurality of semiconductor chips are formed on a wafer. Each of the plurality of semiconductor chips includes a connection pad for connecting to an external terminal. Generally, an integrated circuit (IC) has a structure wherein a plurality of wires are bonded to the pad to be contacted to a lead outside a packaging thereof.
On the other hand, a flip chip includes a bump for a connection to an external connector. The flip chip is flipped in a manner that a surface having the bump faces downward and then press-bonded or heat-bonded to a bonding terminal of an object to be bonded such as a flexible film.
A conventional flip chip bonding method is described below in detail.
FIG. 1 is a flow diagram depicting a conventional flip chip bonding method.
Referring to FIG. 1, a semiconductor wafer is sawed to be divided into a plurality of semiconductor chips and mounted in a wafer holder (S10). A first robot arm having a vacuum suction picks up one of the plurality of semiconductor chips (S20). The picked-up semiconductor chip is flipped by a rotation of the first robot arm (S30). A lower surface of each of the flipped semiconductor chips wherein electrical elements are not formed, i.e. a back surface thereof faces upward. The flipped semiconductor chips are sequentially picked up (S40) by a second robot arm to be disposed on and aligned to an object to be bonded (S50). A front surface of the disposed semiconductor chip faces downward, and a bump formed on the semiconductor chip and a connection area of the object to be bonded are in contact. The disposed semiconductor chip is heated and pressed for bonding (S60).
In accordance with the conventional flip chip bonding method, two processes including a flipping process and a pick & place process of the flipped chip are required. That is, the flipping process wherein the semiconductor chip is picked from the wafer and flipped by the first robot arm and the pick & place process wherein the flipped chip is picked up by the second robot arm to be disposed on the object to be bonded.
Since the two processes are carried out by the robot arms, a time taken while moving of the robot arm is relatively long. In addition, a cost for installing the two robot arms is high, and a complexity of a bonding apparatus is increased. Particularly, a production per hour is decreased as the time taken while moving of the robot arm is increased. That is, a productivity is decreased due to the robot arm. The productivity is an index for measuring a competitiveness of a manufacturing company as well as having a great effect on a manufacturing cost of a product, which is a most important factor of a survival of the manufacturing company.
Therefore, various methods for increasing the productivity are proposed. However, due to a characteristic of the flip chip wherein the semiconductor chip should be flipped, a method that overcomes the above-described problem is not available.